An Iterative Contouring Error Compensation Scheme for Five-Axis Machine Tools Based on Motion Synchronization Control

Contouring error is a critical performance metric for five-axis computer numerical control (CNC) machine tools, primarily arising from system response delays and dynamic coupling among different axes. To effectively suppress contouring error, a novel iterative contouring error compensation method based on motion synchronization control is proposed in this article. First, the motion synchronization points for each axis at identical delay times are determined through numerical calculations. Then, the reference trajectory is iteratively compensated based on these synchronization points and a designed disturbance function approximator. This method takes effect directly in the machine tool coordinate system, avoiding the contouring error estimation and achieving higher compensation accuracy. Comparative experiments on a five-axis CNC machine tool show that the proposed scheme can effectively enhance contouring accuracy, particularly for complex trajectories with high curvatures and sharp corners. Furthermore, in side milling operations, where tool tip position remains basically unchanged while the tool orientation varies, the proposed scheme remains effective, while existing methods tend to fail.